From a0b0a3c6a57097d56c5c471e5cb72bbde8198da8 Mon Sep 17 00:00:00 2001
From: Robin Krahl <robin.krahl@ireas.org>
Date: Tue, 8 Jan 2019 02:11:55 +0000
Subject: Implement message boxes using the dialog backend

This patch adds a first dialog box type, message boxes, and a first
backend, the dialog(1) tool.  It does not yet address the problems of
output handling and backend selection.
---
 src/lib.rs | 134 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 134 insertions(+)

(limited to 'src/lib.rs')

diff --git a/src/lib.rs b/src/lib.rs
index fd09812..67bef2d 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -1,2 +1,136 @@
 // Copyright (C) 2019 Robin Krahl <robin.krahl@ireas.org>
 // SPDX-License-Identifier: MIT
+
+#![warn(missing_docs, rust_2018_compatibility, rust_2018_idioms, unused)]
+
+//! Displays dialog boxes using various backends.
+//!
+//! The `dialog` crate can be used to display different types of dialog boxes.  The supported types
+//! are:
+//! - [`Message`][]: a simple message box
+//!
+//! These dialog boxes can be displayed using various backends:
+//! - [`Dialog`][]: uses `dialog` to display ncurses-based dialog boxes (requires the external
+//!   `dialog` tool)
+//!
+//! You can let `dialog` choose the backend by calling the [`show`][] method on a dialog box.  If
+//! you want to choose the backend yourself, create a backend instance and pass it to
+//! [`show_with`][].  You can also use the [`default_backend`][] function to create a backend.
+//!
+//! # Examples
+//!
+//! Show a message box using the default backend:
+//!
+//! ```no_run
+//! use dialog::DialogBox;
+//!
+//! dialog::Message::new("Did you know that I am using the dialog crate?")
+//!     .title("Public Service Announcement")
+//!     .show()
+//!     .expect("Could not display dialog box");
+//! ```
+//!
+//! Show a message box using the [`Dialog`][] backend with customized settings:
+//!
+//! ```no_run
+//! use dialog::DialogBox;
+//!
+//! let mut backend = dialog::backends::Dialog::new();
+//! backend.set_backtitle("dialog demo");
+//! backend.set_width(100);
+//! backend.set_height(10);
+//! dialog::Message::new("Did you know that I am using the dialog crate?")
+//!     .title("Public Service Announcement")
+//!     .show_with(&backend)
+//!     .expect("Could not display dialog box");
+//! ```
+//!
+//! [`Message`]: struct.Message.html
+//! [`Dialog`]: backends/struct.Dialog.html
+//! [`default_backend`]: fn.default_backend.html
+//! [`show`]: trait.DialogBox.html#method.show
+//! [`show_with`]: trait.DialogBox.html#method.show_with
+
+/// Backends that display dialog boxes.
+///
+/// All backends implement the [`Backend`][] trait.  Some backends might provide additional
+/// settings.  For a list of supported backends, see the [top-level crate documentation](./..) or
+/// the [list of structs in this module](#structs).
+///
+/// [`Backend`]: trait.Backend.html
+pub mod backends;
+
+use std::io::Result;
+
+/// A dialog box that can be shown using a backend.
+///
+/// Some dialog boxes might return data of the type `Output`.
+pub trait DialogBox {
+    /// The type of the data returned by the dialog box.
+    type Output;
+
+    /// Shows this dialog box using the default backend.
+    ///
+    /// `box.show()` is a shorthand for `box.show_with(&default_backend())`.
+    fn show(&self) -> Result<Self::Output> {
+        self.show_with(&default_backend())
+    }
+
+    /// Shows this dialog box using the given backend.
+    fn show_with(&self, backend: &impl backends::Backend) -> Result<Self::Output>;
+}
+
+/// A message box.
+///
+/// This dialog box displays a text and an optional title and has a single OK button.  It does not
+/// produce any output.
+///
+/// # Example
+///
+/// ```no_run
+/// use dialog::DialogBox;
+///
+/// dialog::Message::new("The operation was successful.")
+///     .title("Success")
+///     .show()
+///     .expect("Could not display dialog box");
+/// ```
+pub struct Message {
+    text: String,
+    title: Option<String>,
+}
+
+impl Message {
+    /// Creates a new message box with the given text.
+    pub fn new(text: impl Into<String>) -> Message {
+        Message {
+            text: text.into(),
+            title: None,
+        }
+    }
+
+    /// Sets the title of this message box.
+    ///
+    /// This method returns a reference to `self` to enable chaining.
+    pub fn title(&mut self, title: impl Into<String>) -> &mut Message {
+        self.title = Some(title.into());
+        self
+    }
+}
+
+impl DialogBox for Message {
+    type Output = ();
+
+    fn show_with(&self, backend: &impl backends::Backend) -> Result<Self::Output> {
+        backend.show_message(self)
+    }
+}
+
+/// Creates a new instance of the default backend.
+///
+/// The current implementation always returns a [`Dialog`][] instance.
+///
+/// [`Dialog`]: backends/struct.Dialog.html
+pub fn default_backend() -> impl backends::Backend {
+    backends::Dialog::new()
+}
-- 
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